if you have just dyed your hair dark brown and try what the above answer read,you will probably end up with orange/yellow hair.as you have tinted it a dark colour,it will need a proffessional highlift bleach and 40vol peroxide,if you buy some bleach from a chemist it will not be strong enough to lift out the tint you have just applied.also you will need to leave it on for at least 40 minutes and it still may remain yellowy.if i was you i would keep the top layer of your fringe brown,and lift the underneath section instead.you then dont have to put the bleach up to your scalp(this can tend to bleed on the rest of your hair and leave tiger stripes if you dont know what you are doing,and could burn your scalp).
section your fringe in half,say clip up the top about1-2inches.
underneath apply the bleach in small sections so you have it fully covered,taking care not to go up to your hairline/scalp,dont worry once you let down the top of your fringe it will cover the line,wrap in foil and keep checking it,you can leave bleach for up to 50minutes but you will need proffessional bleach.good luck!